Based on Cyanogen, Euphoria OS custom rom is only supported on Oneplus one and Nexus devices, but in this guide, I would brief you on how you can manually update your android OS to v5.1.1 lollipop via Euphoria OS.

Note: You can install this rom on all Galaxy S4 variate, and make sure you have the latest TWRP recovery installed on your device. The ROM is quite stable and pre-rooted.

Warning: Installation of Custom ROM on your android device voids its warranty, so following the instruction is at your own risk. The guide is strictly advised for pros or technically talented users to give a try.

NB: Also try to back up your files before you proceed to the below guide to avoid loss of data.

-Now, go to the recover main menu, and then choose install ZIP, and then select the Euphoria OS zip file and install immediately. Also do same for the Gapps zip file.

-Once the installation process is completed, simply go back main recovery menu and tap on Reboot system, and your device would be rebooted.

Once your Galaxy S4 is successfully rebooted, then you would notice the new experience of Android 5.1.1 Lollipop on your device with much amazing features. You can go to settings >> about phone, to confirm installation.